Just your average gathering of folks who like to ride at high speed and shout, "Zoobomb!" IMAGE: BRANDON HARTLEY

But the bike club, known for its weekly plummets each Sunday from the Oregon Zoo through Washington Park, faces a few growing pains.

Some in the self-described "anarchist" club fear the downside of more riders: New, inexperienced members are more likely to get hurt, which could re-attract attention from critics and reignite past frictions. Others worry about a new and even more dangerous route that's gaining cachet on U.S. 26.

But first, a little background on the cultural phenomenon Zoobomber Ben "Polyhead" Smith describes as having "no real organization [or] goals other than to ride down the hill on a bike."

The club began locally in 2002 when Zach Archibald, fresh off a bus from Texas, met a few people who rolled up on mini-bikes outside Rocco's Pizza at Southwest 10th Avenue and Oak Street. They eventually took Archibald up to Washington Park to go bombing, and the club fell together once word got out.

Zoobombers are mostly teenagers and twentysomethings, with an occasional older rider thrown in. Skateboarders, longboarders and riders of "assacres" (low-rider scooters) have also joined in the weekly run, which routinely draws over a hundred people and has lured riders from as far away as Britain, South America and Japan.

In April, the club appeared on Globe Trekker, a public-TV travel show broadcast worldwide (the Pacific Northwest episode was rerun this month on OPB). Now Archibald says he's fielding media requests and other inquiries at odd hours.

"I've been getting calls from all over the place," says Archibald, a.k.a. "The Hundredth Monkey" (members often adopt code names).

"We're kind of keeping bike culture on the popular radar," adds "Solid Gold," a three-year member. "And reminding people that bikes are the most fun invention on Earth."

Not everyone welcomes that extra attention,

"The people that are going 35-mph-plus have backgrounds in BMX, mountain biking, bike messengering or downhill skateboarding," says member Mark "SKIDmark" Verno. "I don't know that people showing up for the first time understand this."

Over the years, riders have occasionally broken bones, lost teeth and suffered concussions.

Other members are also concerned about the "Hellway," a newer route that sends a spinoff group of intrepid Zoobombers blasting down an eastbound shoulder of Highway 26 at speeds they claim top 50 mph. While legal, they worry that these rides could lead to disaster.

Portland Police spokesman Sgt. Brian Schmautz says he hasn't heard about any problems with the club in "many months," such as Southwest residents' previous complaints about late-night noise from the bikers shouting "Zoobomb." And TriMet spokesman Bruce Solberg says that agency's clashes with the club over fare payment and bike stowing (see "Speed Demons," WW, June 25, 2003) have long been overcome.

As for the Zoobombers, they stress that they're not out to cause problems for anybody.

"We're not political. We don't want to subvert your dominant paradigm," Archibald says. "We just want to have a good time."

For more information on the Zoobombers, visit http://www.zoobomb.org.